#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>

int main()
{
	int i = 0;
	int sum = 0;
	/*
	while ( i <= 100)
	{
		if (i % 2 == 0)
			sum += i;
		else
			sum -= i;
		i++;
	}
	*/

	for ( i = 1; i <= 100; i++)
	{
		sum += i;
	}
	printf("%d\n", sum);

	return 0;
}